Amongst growers in the US, the UK, Australia, and France, there has been a competition since the 1990s to grow the hottest chili pepper. Chili pepper species and cultivars registering over 1,000,000 Scoville Heat units (SHU) are called "super-hots". Past Guinness World Record holders (in increasing order of hotness) include the Infinity chili, Trinidad Moruga scorpion, Naga Viper pepper, Trinidad Scorpion Butch T, and Carolina Reaper. The current record holder, declared in 2023, is Pepper X, at more than 2.69 million SHU.

Before the early 1990s, there were only two peppers which had been measured above 350,000 SHU, the Scotch bonnet and the habanero. California farmer Frank Garcia used a sport of a habanero to develop a new cultivar, the Red Savina (C. chinense), which was measured at 570,000 in 1994. At the time, this was considered representative of an upper limit of chili pepper hotness.

In 2001, Paul Bosland, a researcher at the Chile Pepper Institute at New Mexico State University, visited India to collect specimens of ghost pepper, also called the Bhut Jolokia or Naga king chili, traditionally grown near Assam, India, which was being studied by the Indian army for weaponization. When Bosland grew and tested the pepper, he discovered it measured over 1 million SHU. According to Bosland, this "kind of opened the floodgates". In 2006, the Dorset Naga (a subspecies of the Naga Morich) was claimed to be the hottest. In 2012, the Chili Pepper Institute called the Trinidad Moruga scorpion the new hottest pepper, saying it had been measured at 2 million SHU, the first time the 2-million mark had been reached.

Many of the cultivars developed in the attempt to produce ever-hotter peppers are hybrids of chilies traditionally grown in India and Trinidad.

The new peppers have been termed "super-hots". Super-hots are classified as peppers registering over 1 million SHU.

In 2015, Bosland and his team, using fluorescence microscopy, found that super-hots not only have more capsaicin than other peppers, but also store their capsaicin differently. While for most peppers removing the pith and seeds also removes much of the heat, for super-hots this is not true, as they tend to store as much in their flesh as they do in their pith. In their report, Bosland et al. call it a "novel discovery that these 'super-hot' chili peppers have developed accessorial vesicles on the pericarp tissue in addition to the vesicles on the placental tissue, thus leading to exceedingly high Scoville heat units for these plants."

Super-hots should be handled with gloves and using eye protection, as contact with even a single seed can cause skin irritation via chili burn.

Chili growers compete with one another, often "ruthlessly", to create the world's hottest pepper. According to Marc Fennell, creator of podcast It Burns, the competition is "a hugely controversial war – there are scandals, accusations of cheating, death threats." According to Maxim, the race has "ignited heated debate" among chiliheads and raised "deep questions about science, ethics, and honor." Whilst competition mainly takes place among British, Australian, and American growers the competition in the US is noted for its "negativity and fighting."